72 Copyright 2016 Korean Neurotraumatology Society

Introduction

Management of intracranial pressure (ICP) is the main goal for patients with traumatic brain injury. Moreover, di-rect injury, secondary insult due to post-traumatic increase of ICP or decrease in cerebral perfusion pressure are well recognized as potential causes of increasing mortality and

morbidity.4,6,7) Decompressive craniectomy (DC) is an im-portant method to decreased ICP,9) and DC is widely per-formed throughout the world.10) This surgical procedure is performed by any neurosurgeons or even residents under training, so it should achieve enough decompression with-out interoperator differences, but textbook only comment-ed that the bone flap should not be just as large as possi-

A Faster and Wider Skin Incision Technique for Decompressive Craniectomy: n-Shaped Incision for Decompressive Craniectomy

Ho Seung Yang, MD1, Dongkeun Hyun, MD, PhD1, Chang Hyun Oh, MD, PhD2, Yu Shik Shim, MD1, Hyeonseon Park, MD1, and Eunyoung Kim, MD, PhD11Department of Neurosurgery, Inha University School of Medicine, Incheon, Korea 2Department of Neurosurgery, Guro Cham Teun Teun Hospital, Seoul, Korea

Objective: Decompressive craniectomy (DC) is a useful surgical method to achieve adequate decompression in hyperten-sive intracranial patients. This study suggested a new skin incision for DC, and analyzed its efficacy and safety.Methods: In the retrograde reviews, 15 patients underwent a newly suggested surgical approach using n-shape skin inci-sion technique (Group A) and 23 patients were treated with conventional question mark skin incision technique (Group B). Two groups were compared in the terms of the decompressed area of the craniectomy, protruded brain volume out of the skull layer, the operation time from skin incision to bone flap removal, and modified Rankin Scale (mRS) which was evalu-ated for 3 months after surgery. Results: The decompressed area of craniectomy (389.1 cm2 vs. 318.7 cm2, p=0.041) and the protruded brain volume (151.8 cm3 vs. 116.2 cm3, p=0.045) were significantly larger in Group A compared to the area and the volume in Group B. The time interval between skin incision and bone flap removal was much shorter in Group A (23.3 minutes vs. 29.5 minutes, p=0.013). But, the clinical results were similar between 2 groups. Group A showed more favorable outcome proportion (mRS 0-3, 6/15 patients vs. 5/23 patients, p=0.225) and lesser mortality cases proportion 1/15 patients vs. 4/23 patients, but these differences were not significantly observed (p=0.225 and 0.339).Conclusion: DC using n-shaped skin incision was a feasible and safe surgical technique. It may be an easier and faster method for the purpose of training neurosurgeons. (Korean J Neurotrauma 2016;12(2):72-76)

KEY WORDS: Dermatologic surgical procedures Decompressive craniectomy Surgical procedures, operative Surgical flaps.

CLINICAL ARTICLEKorean J Neurotrauma 2016;12(2):72-76

pISSN 2234-8999 / eISSN 2288-2243

https://doi.org/10.13004/kjnt.2016.12.2.72

Received: August 12, 2016 / Revised: October 1, 2016 / Accepted: October 10, 2016Address for correspondence: Dongkeun HyunDepartment of Neurosurgery, Inha University School of Medicine, 27 Inhang-ro, Jung-gu, Incheon 22332, KoreaTel: +82-32-890-2370, Fax: +82-32-890-2374, E-mail: dkhyun@inha.comAddress for correspondence: Chang Hyun OhDepartment of Neurosurgery, Guro Cham Teun Teun Hospital, 547 Siheung-daero, Guro-gu, Seoul 08392, Korea Tel: +82-70-4269-2162, Fax: +82-2-851-9400, E-mail: dhckdgus@naver.comDongkeun Hyun and Chang Hyun Oh contributed equally to this work and should be considered co-corresponding authors. cc This is an Open Access article distributed under the terms of Creative Attributions Non-Commercial License (http://creativecommons.org/li-censes/by-nc/3.0/) which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is prop-erly cited.

Ho Seung Yang, et al.

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ble.3) The authors considered that the skin incision could interfere the size of enough decompression area, and con-sidered new skin incision technique what we called the n-shaped skin incision. The purpose of this study is to suggest a new skin incision technique for decompressive surgery to promote greater decompression, and compared the effica-cy and safety of this new technique compared to the con-ventional surgical technique.

Materials and Methods

This retrograde review study was conducted among pa-tients suffering from severe traumatic brain injury. The surgical indication of space-occupying severe traumatic brain injury was as follows: a midline shift of the cerebral structures and parenchymal hypodensity in greater than 50% of the middle cerebral artery territory, which are both identified on computed tomography (CT) scanning.2,5) A to-tal of 38 patients, who underwent decompressive surgery in single university hospital between May 2012 and De-cember 2014, were recruited for this study. These patients were classified into 2 groups: Group A (n=15) which the pa-tients were underwent n-shaped skin incision, and Group B (n=23) which the patients who underwent the conven-tional surgical method (question mark skin incision). All patients were managed promptly after the surgical interven-tion, such as the medical treatment and acute care from ad-mission to post-operation.

The overall surgical method was similar except the skin incision techniques. All patients were endotracheal intu-bated under general anesthesia. In Group A, an n-shaped skin incision was made and included the slightly curved line along the frontal hair line and the parabola line pass through the parietal and temporal regions on the operation side as presented in Figure 1A. In Group B, a large skin in-cision was made and included the frontal, parietal, and tem-

poral regions on the side which similar shape to question mark, and the incision was made as wide as possible (Figure 1B). The soft tissue flap was elevated and retracted by the standard techniques in both groups, and the dura was fixed at the edge of the craniotomy to prevent epidural bleeding. The dura was opened with a large asterisk-shaped incision that involved the frontal, parietal, and temporal lobes. Ly-ophilized cadaver dura was placed underneath the incised dura, and it was secured with several sutures. The bone flap was frozen and stored.

The area of the decompressed regions (cm2) (Figure 2A), protruded brain volume (cm3) (Figure 2B) out of the skull surface, and the time interval between skin incision and bone flap removal were compared. The area of the decom-pression region was approximately calculated by the fol-lowing equation: A (area, cm2)=D * d * ; D was the an-teroposterior diameter of the bone f lap; d was the perpendicular diameter to D from the superior craniectomy margin to the inferior margin in centimeters. The protrud-ed brain volume protruding out of the skull surface is sim-ply calculated by the following equation: V (volume, cm3)= 1/3 * A * H; A is the area of the bone flap; and H is the height of the outward of the brain on CT from the level of the center of the bone flap in centimeters. The time interval between skin incision and decompression time was calcu-lated using the anesthetic medical record (minutes).

Patients outcomes were clinically evaluated according to the modified Rankin Scale (mRS) for 3 months after sur-gery. Surgical mortality was defined as death within 30 days after the procedure. A favorable outcome and poor outcome were defined as mRS 0 to 3 (moderate disability

FIGURE 1. (A, B) Skin incision variation between Group A (n- shaped incision) and Group B (large question mark incision), in-cluding the frontal, parietal, and temporal regions.

BA

FIGURE 2. The area of the decompression region (A) and the protruded brain volume (V) protruding out of the skull surface were approximately calculated by the following equation: A (area, cm2)=D * d * ; D was the anteroposterior diameter of the bone flap; d was the perpendicular diameter to D from the superior craniectomy margin to the inferior margin in centime-ters; V (volume, cm3)=1/3 * A * H; A is the area of the bone flap; and H is the height of the outward of the brain on com-puted tomography from the level of the center of the bone flap in centimeters.

74 Korean J Neurotrauma 2016;12(2):72-76

n-Shaped Incision for Decompressive Craniectomy

or better), and mRS 4 to 6 (severe disability or death). All values were processed with SPSS 12.0 software (SPSS Inc., Chicago, IL, USA) and are expressed as the meanstan-dard deviation (SD). The measurements and outcomes be-tween 2 groups were analyzed by Mann-Whitney U test and chi-square test. Statistical significance was set at p lesser than 0.05.

Results

Table 1 summarized the demographic data for both groups. No significant differences between the 2 groups regarding age, sex, diagnosis, and the initial neurologic scores were observed. The area of craniectomy was larger in Group A (389.145.7 cm2) than that in Group B (318.756.5 cm2, p=0.041). The protruded brain volume out of the skull sur-face was 151.8117.7 cm3 in Group A and 116.281.3 cm3 in Group B, indicating that more decompression was per-formed in Group A (p=0.045). In addition, the time inter-val between skin incision and bone flap removal was much shorter in Group A (23.313.7 minutes vs. 29.515.1 min-utes, p=0.013).

There were no surgery-related complications except for 1 patient in Group A and 3 patients who had a postoperative epidural hematoma (EDH) and subsequent EDH evacua-tion (p=0.531). The clinical outcomes throughout the 3 month after surgery were as follows: In Group A, 6 (40.0%) out of 15 patients had favorable outcomes (mRS 0-3) and 1 (6.7%) patie